Fix the type of some values passed to MySQL

Summary: Ref T3377. MySQL ignores indexes if we hand it mismatched datatypes. This seems colossally dumb, but give it what it expects.

Test Plan: wat

Reviewers: wez, btrahan

Reviewed By: wez

CC: aran

Maniphest Tasks: T3377

Differential Revision: https://secure.phabricator.com/D6201
Expand the "PhabricatorExternalAccount" table for new registration

Summary:
Ref T1536. This is the schema code for `PhabricatorExternalAccount` which was previously in D4647. I'm splitting it out so I can put it earlier in the sequence and because it's simple and standalone.

Expands `PhabricatorExternalAccount` to have everything we need for the rest of registration.

Test Plan: Implemented the remainder of new registration on top of this.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T1536

Differential Revision: https://secure.phabricator.com/D6169
Remove OAuth token/expiry interfaces

Summary:
Ref T1536. Currently, we store OAuth tokens along with their expiry times and status. However, all we use this for is refreshing profile pictures and showing a silly (and probably somewhat confusing) interface about token status.

I want to move this storage over to `PhabricatorExternalAccount` to make the cutover easier. Drop it for now, including all the profile image stuff (I plan to rebuild that in a more sensible way anyway).

Test Plan: Viewed screen; linked/unlinked accounts.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T1536

Differential Revision: https://secure.phabricator.com/D6170
Internalize storage access for PhabricatorUserOAuthInfo

Summary:
Ref T1536. Move all access to the underlying storage to inside the class. My plan is:

  - Migrate the table to ExternalAccount.
  - Nuke the table.
  - Make this class read from and write to ExternalAccount instead.

We can't get rid of OAuthInfo completely because Facebook still depends on it for now, via registration hooks.

Test Plan: Logged in and registered with OAuth.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T1536

Differential Revision: https://secure.phabricator.com/D6171
Migrate the OAuthInfo table to the ExternalAccount table

Summary: Ref T1536. Migrates the OAuthInfo table to ExternalAccount, and makes `PhabricatorUserOAuthInfo` a wrapper for an ExternalAccount.

Test Plan: Logged in with OAuth, registered with OAuth, linked/unlinked OAuth accounts, checked OAuth status screen, deleted an account with related OAuth.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T1536

Differential Revision: https://secure.phabricator.com/D6172